Recombinomics: High School Absenteeism Linked To H1N1 Wave 3 Start

Blood tests on Pittsburgh residents found 45 percent of people aged 10 to 19 years had antibodies against the new H1N1 flu strain. About 22 percent of people across all groups developed immunity to the virus by early December and a quarter of those born in the 1920s may have already had protective antibodies before the pandemic resulting from prior flu infection, researchers at the University of Pittsburgh found.

The above comments on H1N1 antibody frequencies in Allegheny County indicate that H1N1 rapidly spread through the Pittsburgh, Pennsylvania metropolitan area last fall, especially among school aged children, aged 10-19. Although there were few school closures or deaths a few schools were highlighted in media reports and in one middle school daily absenteeism rates were between 19-29% for at least 9 days, suggesting attack rates approached 100% since many who were affected did not develop a high fever and were not absent.

Other areas reported closures of entire school districts suggesting these high levels were present nationwide during the fall peak in activity. That peak began with school opening in August for many areas of region 4, and recent reports suggest a new wave may have begun there which has now started to spread nationwide. Although media reports had announced the end of the pandemic and some politicians questioned whether there was a pandemic, prior pandemics had a fall and winter wave and eliminated the seasonal flu that had been circulating.